Texture looks grainy in cycles render (not fireflies)
Ok, after looking at your nodes, scene, and the images it all came down to two small values. (They were also the only things you have different from the tutorial)



The most important setting here is the  Strength of the Bump node. One is too strong in almost every case. Andrew uses 0.1, but I used 0.15, either way, turn it down and you will see it look much better.

The second setting you want to change is the Roughness of the Glossy BSDF node. The default 0.2 is kind of rough, and you might not even see the reflections at all. Both Andrew and I use 0.1, which may not sound like much but on the scale of Pure mirror to diffuse, .1 makes a big difference.

Here is the exact same scene, only difference is the strength of the roughness in the glossy shader. 0.1 is on the left, and 0.2 is on the right.


Notice with the more scattered, or diffused (0.2) value the reflection just mix in and you really cant tell what should be reflecting.